Many chairs are currently produced which comprise a base, often provided with castors, and a single column supporting the chair seat. Often, some means of adjusting the height of the column is provided. In more sophisticated chairs of this kind, the column is telescopic and is urged to elongate by the pressure of gas contained in a reservoir, latch means controlled by a lever being provided to lock the column in a desired position.
The present invention relates to improvements in seat columns of this kind and has particular but not exclusive application to seat columns in which elongation of the column is urged by a spring rather than by compressed gas.
In particular, the present invention relates to variable length columns e.g. support columns for mounting seats on bases to form variable height seats, comprising:
first and second elongate members longitudinally slidable together or apart to shorten or to extend the column;
means acting directly or indirectly between the first and second elongate members to tend to lengthen the column;
at least one latch member associated with one of the first and second elongate members and displacable to engage against the other of said first and second elongate members at any one of different extensions of the column to lock the column at said extension;
and means for selectively displacing said latch member or members to lock the column and for releasing said latch members to permit reverse displacement thereof to free the column.